Snap gauge



p i 1940- H. v. TGRNEBbl-IM 2.197.115

' SNAP GAUGE Filed July 2, 1936 2 Sheets-Sheet 2 I INVENTOR. HlldlngValdemar Tiirnebohm 1s ATTORNEY.

. All! greatest diameter of the work,

Patented Apr. 16, 1940 assigno r to Aktiebolaget 'SvenskaKullagerl'abriken, Goteborg, Sweden, a corporation of Sweden ApplicationJuly 2, 1936, Serial No. 88584 In Sweden May 29, .1936

v 3'Claims. (01. 33-463) The purpose of the present invention is toprovide a gauge which is easier of adjustment than gauges of thehitherto usual type and which can be adjusted to a plurality ofdifferent nominal sizes while retaining the same anvil. Another purposeof the invention is to provide a snap gauge i'vhichinsures thatall partsof the surface ofthe work are within fixed tolerances. A. still furtherpurpose'of the' invention is to provide a snap gauge of ;a type inwhich. gauges of a considerable range of nominal sizes can. lie-madefrom a single or, onlya few different types or sizes of'hlanks. Finallythe space required by the gauging surfaces along the length of theshanks of the gauge is lessthan in gauges of the usual type, whereby thegauge can be made more rigid. I

In a snap gauge according to the invention, one oi these anvils has aplane surface, while the other anvil has a surface with a convex profilein the plane "of the gauge. For gauging the high limit of: the work thevlatter anvil is preferably given the form of a portion of a cylinder,the axis of which is parallel withthe axis of the work, and

for gauging thelow limit the gauging surface-of the anvil is ofcomparatively small extensioziin an axial direction of the work, ispreferably convex in form and "may torm part of .a spherical surface.Since one of the anvils has a cylindrical surface, its adjustment willbe very much simpler "than will be the case with snap gauges of the typehitherto in use, since it is only necessary to attain parallelism in onedirection instead of as previously in two directions perpendicular toeach other. Hereby a still further advantage is attained, namely thatthe gauge can be easily made adjustable, since it is not necessary toconsider parallelism in a direction perpendicular to the axis of thework. By making the gauging surface of one of theanvils on the low limitside of comparatively small-length in an axial direc- 1 tion it ispossible to gauge the-diameter of the work in a plurality of planes.

"One form of the invention is illustrated on the accompanying. drawingsin which:

Figure 1 shows aside view of a snap gauge,

Figure 2 shows an end view of a portion of the gauge during theopera-tiontof gauging and illustrates how the comparatively longcylindrical gauging surface on the high limit side gauges the Figure 3shows a similar View and illustrates how the short gauging surfa'ceofthe low limit side gauges the smallest diameterf thework, I

' Figure 4 shows a corresponding view of a gauge for gauging the lowlimit and provided with two gauging surfaces on one of the anvils,

1 Figure 5 shows a plan of'an anvil for a tolerance snapi gauge, and

Figure 6 shows a blankfor the production of a series ofsnap gauges ofdifferent nominal sizes.

The frame part of the snap gauge'illustrated in the figures is horseshoeshaped or U-shaped andhas a portion l comprising the bow of the Uwhich is' capable of being sprung under pressure. It also has shanksQand .3 to which are .fixed anvils i. and 5. One of the :anvils 5 has .aplane gauging surface 28 while the other anvil A has a gauging surface.6, which together with the surface "determines the high limit, and .a

gauging surface I, whichtogether with the gaug ing surface 20 determinesthe low limit. The

surface 6 has the form of a relatively long circular cylinder, while thesurface 7 comprises two convex surfaces. The convexity of the surfaces 1greatly facilitate adjustment of the gauge, since theamounts of materialwhichmust beremoved are considerably less than in the case with theusual relatively large plane surfaces I The an vils are fixed to theshanks by means pins 24' and carried'hy their rear surfaces which arepressed into holes '22. and 23 in the shanks. The anvil "4 is located sothat the cylindrical surface 6 is perpendicular to the direction ofapplying the device in gauging.

The nominal gauging dimension of the snap gauge is determined by meansof a screw device comprising a double ended screw t the ends of whichpass through holes 9 and ill in the-shanks 2 and 3 and are threaded fornuts ll and :12.

The inner sides of the nuts are spherical and engage-correspondingspherical surfaces 15:3: and M on the shanks so that there will' alwaysbe 'surface contact between the .nuts and the surfaces l3 and Mindependent of the size of the anglebetween the shanks 2 and '3. Washers1J5 and 16 are disposed on the screw ill between the. :shan'ksZ and 3.The outer surfaces of thewashers .are -.spherical and engagecorresponding spherical surfaces I! and 118 on the inner sides of theshanks. The play between the holes of the washers l5 and tend the screw:8 is comparatively great, whereby the washers-are free to .move in aradial direction. relative to ;the screw and adjust themselves so thattherezis al-' ways proper surface contact between the wasl'lers and .theshanks. Between the washers i5 and it is disposed .a distance sleeve l9;which is horseshoe shaped in cross section. In other, words, thetsleeveis :open at one siclefso ithat'it can be tapering and the diameter Dabrought into place sideways to surround the nominal sizes, whereby,however, the tolerance zone is determined by the form and dimensions ofthe anvil 4.

The operation of gauging diameters with the new snap gauge is carriedout in the same manner as with snap gauges of the hitherto used types.Figure 2 shows the operation of gauging a work piece having one of itsdiameters D1 in the vicinity of its central plane greater than thediameters D2 and D3 atthe ends of thework piece. The figure illustratesthe manner in which the snap gauge gauges the greatest diameter D1 forthe reason that the gauging surfaces on the high limit side havecomparatively long straight surfaces consisting of a plane surface onthe one side and of a relatively long cylindrical surface on the outerside. Such cylindrical surface is long relative to the surface forgauging the surface for the minimum dimension, and is made as long asmay be convenient, although its length is naturally limited forpractical reasons. The surface for gauging the main'mum dimension ismade as long as is practicable and the surface for gauging the minimumdimension as short as is practicable.

Figure 3 illustrates how it is possible to discover a concavity of thework piece. With the aid of a gauge of the usual type, in which thegauging surfaces of the low limit side comprise only two relativelygreat plane surfaces, it would only be possible to gauge the greatestdiameters D6 and D7 of the work piece of Figure 3, without discoveringthat one of the diameters D5 is less than the low limit. With the gaugeaccording to the invention, on the other hand, it is possible todiscover such inaccuracies, since the length of one of the gaugingsurfaces l is comparatively small.

The gauge according to Figure 4 has two gauging surfaces instead of one,as is the case with the gauge according to Figure 3. The surfaces 1 ofFigure 4 are located at some distance from each other in the directionof the axis of the work. Since the surfaces 1 are located near the sideplanes of the shanks 2, it is possible to gauge diameters close toshoulders etc.

Since there are two gauging surfaces located at some distance from eachother, it is possible to discover conicity of the work piece. exampleillustrated in Figure 4 the work piece is is shown to be greater thanthe diameter D9. If the diameter D8 is within the determined tolerancelimits, the surface of the work piece will contact with the gaugingsurface '5 on the left hand side of the figure, while the other diameterD9, if it is less than the low limit, will freely pass the other gaugingsurface 8. When carrying out the gauging operation the gauge will,therefore, have a tendency to swivel about that one of the gaugingsurfaces 1 which comes into contact with the work.

The anvil of Figure 5 may be used for gauging would result.

In the a work piece such as is shown in Figure 3 in the direction ofgauging represented in that figure.

If one of the gauging surfaces for gauging the jother words, one of thesurfaces for gauging the minimum dimension would pass over the workpiece, while the other surface would be arrested and a certain tiltingmovement of the gauge By making one'of the gauging surfaces plane andthe other gauging surface convex in the direction of gauging it will bepossible, as above pointed out, to adjust the gauge by altering theangle betweenthe shanks by means of the screw device, since it is notnecessary to maintain the gauging surfaces parallel in the direction ofgaug- Y i,

ing. It isherebymade possible to use a blank of a single type and sizefor making gauges of a considerable number of different nominal sizes.

The basic form of the blank is shown in Figure 6. As will be seen fromFigure l, the blank must be bent at its central portion to a certain U-shaped curvature, the size of which within oer-1 I tain limits isdetermined by the desired nominal size of the gauge. The blank shown inFigure 6 may for example be used for gauges having nominal sizes between10 and 30 mm., the same curva tures being used for sizes betweenllO andi8 mm., another curvature for sizes between 18 and 24 and still anothercurvature for sizes between 24 and 30 mm. The nominal sizes of thegauges are then determinedby the length of the distance sleeves I9,whereby the length of the distance sleeves must be adjusted exactly tocorrect length in each separate case. I sizes of blanks it is,therefore, possible to produce gauges having different nominal sizesextending over the whole range of sizes used in practical gaugingoperations with gauges of this type- The distance between thecylindrical and spherical surface on the anvil can be made shortascompared with the corresponding. distance in a gauge with two planesurfaces, where- 'bythe gauge can be made more rigid.

1. A snap gauge consisting of a U-shaped frame comprising a pair ofshanks united by means of an intermediate portion capable of beingsprung, the shanks being interconnected by means of a screw deviceadapted to adjust the relative position of the shanks, and gaugingsurfaces formed on the shanks, there being a distance sleeve disposedbetween the shanks, the length of thesaid distance sleeve determiningthe gauging dimension between the gauging surfaces of the snap gauge,the distance sleeve being U-shaped in section and disposed aboutthescrew device.

2. A snap gauge consisting of a u -shaped frame comprising a pair ofshanks united by means of an intermediate portion comprising the bow ofthe U and capable of being sprung, the shanks being interconnected bymeans of a screw device adapted to adjust the relative position of theshanks, and gauging surfaces formed on the shanks, there being adistance sleeve dis- By using only a. few is posed between the shanks;the length of thesaid. distance sleeve determining the gaugingdim'ehsion between thegauging surfacesof the snap section and disposedabout the screw device, and

two opposed anvils carried by the frame, one of the anvils having aplane gauging surface, the surface of the otheranvil being formed inpart as a cylinder and in part as portions of a pair of spheres.

3. A snap gauge frame of v U-shape, comprising a pair of shanks unitedby means of an intermediate portion capable of being sprung, the

shanks being interconnected by a screw device ,distance sleevedetermining the dimension between the shanks, the distance sleeve beingopen 7 sided and disposed about the screw device.

HJVILDING VALDEMAR ToRNEBoHM.

